diff options
Diffstat (limited to 'checksum.c')
| -rw-r--r-- | checksum.c | 24 |
1 files changed, 19 insertions, 5 deletions
@@ -57,6 +57,7 @@ #include <linux/icmpv6.h> #include "util.h" +#include "ip.h" #include "checksum.h" /* Checksums are optional for UDP over IPv4, so we usually just set @@ -114,13 +115,26 @@ uint16_t csum_fold(uint32_t sum) } /** - * csum_ip4_header() - Calculate and set IPv4 header checksum - * @ip4h: IPv4 header + * csum_ip4_header() - Calculate IPv4 header checksum + * @tot_len: IPv4 payload length (data + IP header, network order) + * @protocol: Protocol number (network order) + * @saddr: IPv4 source address (network order) + * @daddr: IPv4 destination address (network order) + * + * Return: 16-bit folded sum of the IPv4 header */ -void csum_ip4_header(struct iphdr *ip4h) +uint16_t csum_ip4_header(uint16_t tot_len, uint8_t protocol, + struct in_addr saddr, struct in_addr daddr) { - ip4h->check = 0; - ip4h->check = csum(ip4h, (size_t)ip4h->ihl * 4, 0); + uint32_t sum = L2_BUF_IP4_PSUM(protocol); + + sum += tot_len; + sum += (saddr.s_addr >> 16) & 0xffff; + sum += saddr.s_addr & 0xffff; + sum += (daddr.s_addr >> 16) & 0xffff; + sum += daddr.s_addr & 0xffff; + + return ~csum_fold(sum); } /** |